Role of Sodium Ion on TiO₂ Photocatalyst: Influencing Crystallographic Properties or Serving as the Recombination Center of Charge Carriers?

There have been continuing debates about the role of Na⁺ on TiO₂ photocatalyst in the past decades. Most researchers accepted that Na⁺ served as the recombination center of photogenerated electrons and holes. Nevertheless, other opinions also existed, such as Na⁺ increased the crystallite size of TiO₂, Na⁺ hampered the crystallization of anatase TiO₂, and Na⁺ promoted the formation of brookite TiO₂ or titanate sodium. In this research, we have systematically investigated the role of Na⁺ during the fabrication of TiO₂ film and powder through the sol–gel method and studied the influences of crystallinity and the content of Na⁺ on the photocatalytic activities of TiO₂ film and powder. It has been found that the existence of Na⁺ in TiO₂ film and powder should influence their crystallographic properties, in detail, inhibiting the crystallization and growth of anatase phase in TiO₂ film and powder, promoting the formation of brookite phase in TiO₂ film, and increasing the transformation temperature of anatase to rutile phase in TiO₂ powder. Even though the existence of Na⁺ forms the Ti–O–Na bond on the surface of TiO₂, however, the widely adopted hypothesis of Na⁺ serving as the recombination center of photogenerated electrons and holes is not correct

Interface Bonds Determined Gas-Sensing of SnO₂–SnS₂ Hybrids to Ammonia at Room Temperature

Unique gas-sensing properties of semiconducting hybrids that are mainly related to the heterogeneous interfaces have been considerably reported. However, the effect of heterogeneous interfaces on the gas-sensing properties is still unclear, which hinders the development of semiconducting hybrids in gas-sensing applications. In this work, SnO₂–SnS₂ hybrids were synthesized by the oxidation of SnS₂ at 300 °C with different times and exhibited high response to NH₃ at room temperature. With the increasing oxidation time, the relative concentration of interfacial Sn bonds, O–Sn–S, among the total Sn species of the SnO₂–SnS₂ hybrids increased first and then decreased. Interestingly, it can be found that the response of SnO₂–SnS₂ hybrids to NH₃ at room temperature exhibited a strong dependence on the interfacial bonds. With more chemical bonds at the interface, the lower interface state density and the higher charge density of SnO₂ led to more chemisorbed oxygen, resulting in a high response to NH₃. Our results revealed the real roles of the heterogeneous interface in gas-sensing properties of hybrids and the importance of the interfacial bonds, which offers guidance for the material design to develop hybrid-based sensors

DataSheet1_Efficient and reversible Cas13d-mediated knockdown with an all-in-one lentivirus-vector.xlsx

Type VI CRISPR effector Cas13d from Ruminococcus flavefaciens XPD3002 (RfxCas13d) is an RNA-guided RNA endonuclease. RfxCas13d has been harnessed to knockdown gene expression with high specificity in various systems including mammalian cells. While inducible knockdown is advantageous over constitutive knockdown in many scenarios, current inducible systems of RfxCas13d express CRISPR RNA and Cas13d separately. Such systems could be cumbersome to handle and may hamper the application of RfxCas13d in some scenarios. Here, we design an all-in-one Cas13d lentivirus vector which renders efficient and inducible knockdown in a doxycycline dosage-dependent manner. Furthermore, we find that Cas13d has a short half-life in mammalian cells. As a result, knockdown can be promptly reversed after doxycycline withdrawal. This vector is particularly useful for applications involving indispensable genes and/or in cells hard to transduce.</p

Directional Heat Dissipation across the Interface in Anatase–Rutile Nanocomposites

Understanding the structures and properties of interfaces in (nano-)­composites helps to reveal their important influence on reactivity and overall performance. TiO₂ is a technologically important material, and anatase/rutile TiO₂ composites have been shown to display enhanced photocatalytic performance over pure anatase or rutile TiO₂. This has been attributed to a synergistic effect between the two phases, but the origin of this effect as well as the structure of the interface has not been established. Using Raman spectroscopy, here we provide evidence of distinct differences in the thermal properties of the anatase and rutile moieties in the composite, with anatase becoming effectively much warmer than the rutile phase under laser irradiation. With the help of first-principles calculations, we analyze the atomic structure and unique electronic properties of the composite and infer possible reasons for the directional heat dissipation across the interface

Image1_Efficient and reversible Cas13d-mediated knockdown with an all-in-one lentivirus-vector.TIFF

Type VI CRISPR effector Cas13d from Ruminococcus flavefaciens XPD3002 (RfxCas13d) is an RNA-guided RNA endonuclease. RfxCas13d has been harnessed to knockdown gene expression with high specificity in various systems including mammalian cells. While inducible knockdown is advantageous over constitutive knockdown in many scenarios, current inducible systems of RfxCas13d express CRISPR RNA and Cas13d separately. Such systems could be cumbersome to handle and may hamper the application of RfxCas13d in some scenarios. Here, we design an all-in-one Cas13d lentivirus vector which renders efficient and inducible knockdown in a doxycycline dosage-dependent manner. Furthermore, we find that Cas13d has a short half-life in mammalian cells. As a result, knockdown can be promptly reversed after doxycycline withdrawal. This vector is particularly useful for applications involving indispensable genes and/or in cells hard to transduce.</p

Polymorphism in the Hypoxia-Inducible Factor 1alpha Gene May Confer Susceptibility to LDD in Chinese Cohort

<div><p>Objective</p><p>This study aimed to investigate whether or not hypoxia-inducible factor-1α (HIF-1α) gene variants are associated with the susceptibility and clinical characteristics of lumbar disc degeneration (LDD).</p> <p>Methods</p><p>We examined 320 patients with LDD and 447 gender- and age-matched control subjects. We also determined the HIF-1α gene variants, including C1772T (P582S) and G1790A (A588T) polymorphisms.</p> <p>Results</p><p>Significant differences were observed in allelic and genotypic distributions of 1790 A > G polymorphisms between LDD cases and control subjects. Logistic regression revealed that 1790 AA genotypes indicated a protective effect against the development of LDD. The HIF-1α 1790 A > G polymorphisms also affected the severity of LDD as evaluated based on the modified Japanese Orthopedic Association (mJOA) scores. The 1790 AA genotype carriers exhibited significantly lower mJOA scores than AG and GG carriers. C1772T did not show any association with the risk and severity of LDD.</p> <p>Conclusion</p><p>Our study suggested that HIF-1α 1790 A > G polymorphisms may be used as a molecular marker to determine the susceptibility and severity of LDD.</p> </div

Understanding of Electrochemical Mechanisms for CO₂ Capture and Conversion into Hydrocarbon Fuels in Transition-Metal Carbides (MXenes)

Two-dimensional (2D) transition-metal (groups IV, V, VI) carbides (MXenes) with formulas M₃C₂ have been investigated as CO₂ conversion catalysts with well-resolved density functional theory calculations. While MXenes from the group IV to VI series have demonstrated an active behavior for the capture of CO₂, the Cr₃C₂ and Mo₃C₂ MXenes exhibit the most promising CO₂ to CH₄ selective conversion capabilities. Our results predicted the formation of OCHO^• and HOCO^• radical species in the early hydrogenation steps through spontaneous reactions. This provides atomic level insights into the computer-aided screening for high-performance catalysts and the understanding of electrochemical mechanisms for CO₂ reduction to energy-rich hydrocarbon fuels, which is of fundamental significance to elucidate the elementary steps for CO₂ fixation

The VEGF and HIF-1α relative expressions by 1790G>A genotypes.

<p>The VEGF and HIF-1α relative expressions by 1790G>A genotypes.</p

HIF-1α and VEGF protein expression in samples from LDD patients.

<p>HIF-1α and VEGF protein expression in samples from LDD patients.</p

Tuning and Locking the Localized Surface Plasmon Resonances of CuS (Covellite) Nanocrystals by an Amorphous CuPd_<i>x</i>S Shell

We demonstrate the stabilization of the localized surface plasmon resonance (LSPR) in a semiconductor-based core–shell heterostructure made of a plasmonic CuS core embedded in an amorphous-like alloyed CuPd_<i>x</i>S shell. This heterostructure is prepared by reacting the as-synthesized CuS nanocrystals (NCs) with Pd²⁺ cations at room temperature in the presence of an electron donor (ascorbic acid). The reaction starts from the surface of the CuS NCs and proceeds toward the center, causing reorganization of the initial lattice and amorphization of the covellite structure. According to density functional calculations, Pd atoms are preferentially accommodated between the bilayer formed by the S–S covalent bonds, which are therefore broken, and this can be understood as the first step leading to amorphization of the particles upon insertion of the Pd²⁺ ions. The position and intensity in near-infrared LSPRs can be tuned by altering the thickness of the shell and are in agreement with the theoretical optical simulation based on the Mie–Gans theory and Drude model. Compared to the starting CuS NCs, the amorphous CuPd_<i>x</i>S shell in the core–shell nanoparticles makes their plasmonic response less sensitive to a harsh oxidation environment (generated, for example, by the presence of I₂)